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DX6i Tx battery

Plug in pen cells safe or unsafe?

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Steven Brown15/06/2008 23:17:00
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My brother just purchased a spektrum dx6i full range tx that runs on 4 AA cells, i.e 4.8volts we have no concerns about the minimal voltage required to power the tranny as it is 2.4 gig and much more efficient than 35mhz. The problem is that some of the older members of our local club say that a welded nicad pack would be much safer than single cells plugged in on to metal contacts. What is the real deal with these metal to metal contacts? has metalurgy changed in the last two decades? and most importantly where does the B.M.F.A  stand on this subject? views and arguments wanted...........
Tim Mackey15/06/2008 23:21:00
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I would personally never use sprung contact connections in ANY R/C air models - rcvr or tr.

Thats my view - now.... bring on the argument

Eric Bray15/06/2008 23:37:00
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Well.... I've been using those plastic pencell cases from Maplin, with no problems. Mind you I'm not using them in leccy powered models., only slopers, so the current drawn through the contacts isn't that great (I've read Timbo's servo expose!) The only thing I do to ensure connectivity is put an elastic band around the case to ensure the cells cannot pop out in mid-gyration!

What you do have to watch is when you solder the wires to the connector, (I don't use the pp3 plug on things!) because the plastic melts quite readily!

(Stands back, ducks into trench and puts tin hat on) 

Tim Mackey15/06/2008 23:39:00
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tak a tak a tak a tak
260 Flyer16/06/2008 01:15:00
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How many times have you removed the back of your TV remote and "twiddled" the batteries to get it working?
Tim Mackey16/06/2008 08:45:00
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Yo - my point demonstrated rather nicely Rob - apart from the extra weight of the carrier too
Eric Bray16/06/2008 12:37:00
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What weight? About six grammes in the nose, where it saves stuffing a bit of lead?

The only time the back comes off my tv remote is when the boss drops it! How many times do you take your clock off the wall and twiddle the battery to get it going? Or the smoke alarm? Or your watch? (Mines solar powered anyway!)

I remain unconvinced that there IS an argument, for light current usage. None of mine have failed me yet. 

Frank Skilbeck26/06/2008 20:13:00
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Note the batteries in question are in the Tx not the Rx. Lots of RTF which include the TX use individual cells.
Eric Bray27/06/2008 12:36:00
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Yes. My two heli transmitters use loose pencells, one of my ham gear trx's uses loose D cells, my cordless headphones/'puter keyboard, mouse, camera, pocket tranny, radio scanners, all use loose cells. They don't need constant fiddling to keep them working!
Steve Mortimer05/07/2008 12:24:00
11 forum posts

i have used loose cells in my old R/C car TXs and never had a problem, and i have put them through a lot of rough use, knocking them off toolboxes, dropping them, running over the rough field and throguh teh woods with them, never even so much as a glitch.

i had to use a cell holder and 4 NiMh cells on my trainer when i first got it because the bloke i bought it off had "supposedly" put the pack and the electric engine starter that came with it in the post (never turned up, never heard from the guy again) i guess aslong as you do the normal wrapping in foam with an elastic band around them you should have no problems (well, i didnt anyway) 

Tim Mackey05/07/2008 12:29:00
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I stand by my original opinion - land based stuff, and little indoor type helis do not pose the same potential dangers. The BMFA have a firm policy / recommendation on this point and you may well find your Insurance is voided if you fail to follow the "rules" - see page 20 of the BMFA Handbook.
Eric Bray05/07/2008 14:56:00
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We shall agree to differ until such time as someone can actually prove a problem exists!
Tim Mackey05/07/2008 17:43:00
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Well a potential problem exists, more so than with a hard wired battery - that potential is problem is one that is easly and cheaply avoided
Eric Bray05/07/2008 18:15:00
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Yorkman05/07/2008 18:18:00
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well,is it possible to fit a soldered 'block' of 4x AAs into the spektrum transmitter?

I have a DX6i set on my shopping list........

Tim Mackey05/07/2008 19:40:00
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yes - but not the easiest of jobs....and would probably - ironically - invalidate the guarantee !
Frank Skilbeck05/07/2008 21:10:00
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Timbo but the BMFA handbook says that it's OK to use dry cells in the TX and these don't usually come in welded packs. The Spektrum manual says it's OK to replace the dry cells with NiCd's of NiMh's.

Will using the Tx set with non-welded NiMh's invalidate the BMFA insurance, will Horizon Hobbies be responsible in that event as it's included in their manual?

Should RCME be issuing a warning advising people not to fit loose rechargable cells in the DX6i's but continue to use dry cells as advocated by the BMFA?  

Tim Mackey05/07/2008 23:41:00
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The BMFA clearly state that spring loaded battery boxes should not be used.

Perhaps they mean in the actual model  rather than the tr?

However, it was not my intention to get into the BMFA standpoint ( there are many things about the BMFA that I dont agree with anyway ) but I merely stated and stressed, that it was just my personal opinion that using spring loaded battery holders in airborne RC modelling equipment was neither good practice or necessary these days.

I for one am somewhat surprised that the DX6i uses such a battery box - but as this is the standard setup for this model of tr then I expect there will be no problem with Insurance etc

Frank Skilbeck06/07/2008 08:37:00
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Timbo, thanks I'd rather use some high quality rechargables than poundshop dry cells. I would be quite happy fitting a welded pack into the Tx but I'm not sure how that would affect the warranty of the equipment.

I must admit that the battery box supplied seems of good quality and the batteries are very secure.

In the instructions Spetrum state that the DX6i sold separately is normally supplied with rechargable NiMH batteries and overnight charger but when sold as part of a RTF set will come with dry cells. It looks like in the UK they decided not to ship with rechargables and charger (maybe to meet the magic < £100 mark).

They state in the manual that optional NiCd or NiMH 1.2 volt AA cells can also be used and then go to great lengths to warn you of the polarity of the charging jack which is different to say futaba. There are no instructions on fitting a welded pack into the Tx, maybe that could be a technical article in RCME in conjunction with Spektrum.

Ironically I'm only using this set in my small electrics at present and I'm using my 35 set in my larger glow and electric planes. 

260 Flyer06/07/2008 09:39:00
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In my job as an equipment engineer, the majority of electrical/electronic problems I have to deal with are caused by bad contacts on connectors.

Your goal on any system should be to reduce the number of connections to the absolute minimum.

In using 4 loose cells in a battery box you will have 5 critical contacts as opposed to 2 for a hard wired pack. If you use 8 cells you then have 9 chances for a spec of dust or spot of corrosion to spoil your day.

Safe flying and happy landings!

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